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Biomedical subjects

W Krebs

Publications and source records attributed to W Krebs.

At least 91 records · Page 5Linked to original sources
PubMed1980

Left ventricular volume and ejection fraction determination by cross-sectional echocardiography in patients with coronary artery disease: a prospective study.

In a prospective study the accuracy of cross-sectional echocardiography for determination of left ventricular (LV) volume and ejection fraction (EF) was analyzed in 53 patients with coronary artery disease and compared to that of cineangiocardiography (angio). From the apex of the heart phased-array wide-angle (84 degrees) electronic echocardiograms were received in the RAO-equivalent view. Angios were obtained in a 30 degree RAO view. Using Simpson's rule, end-diastolic (EDV) and end-systolic (ESV) LV volumes were calculated and the EF derived. Left ventricular long axis was transected in eight segments, yielding seven diameters. In 50 of the 53 patients cross-sectional echocardiograms could be recorded. The correlation between cineangiocardiography and cross-sectional echocardiography for EDV was highly significant: r = 0.936, y = 0.667x + 27.1, standard error of estimate (syx) +/- 22.2 ml; for ESV: r = 0.970, y = 0.699x + 14.7, syx +/- 14.5 ml; for stroke volume: r = 0.721, y = 0.503x + 11.3, syx +/- 15.3 ml; for EF: r = 0.909, y = 0.740x + 11.3, syx +/- 6.0%. Angio mean long axis was 10.2 +/- 1.2 cm, cross-sectional echocardiographic long axis 8.7 +/- 1.3 cm. Mean LV diameter determined by cineangiocardiography was longer than when determined by cross-sectional echocardiography. The mean difference reached 2.0 cm in the middle of the LV. Our prospective comparative study revealed that LV volumes and EF were underestimated by cross-sectional echocardiography compared to cineangiocardiography because of a methodological systematic error caused by a tangential cut of the heart. In the RAO-equivalent view the "true" long axis was missed. The high corrleation coefficients, however, indicate that the "true" LV volume and EF can be calculated from the given regression equation. Serial measurements should be legitimated.

Angiocardiography↗
PubMed1979

[A new method of pericardiocentesis and quantification of pericardial effusions by echocardiography (author's transl)].

With a new method for safe and complete evacuation of pericardial effusions it was possible to check the quantification of pericardial fluid is was possible to check the quantification of pericardial fluid by echocardiography. Using a formula based on the assumption that in systole the pericardial fluid is distributed equally around the contracting heart (like a coat enveloping a sphere), it was demonstrated that pericardial effusions ranging from 250 to 600 ml could be fairly accurately measured. Smaller effusions were not so readily determined. Effusions over 600 ml could be only roughly measured, usually being underestimated.

Echocardiography↗
PubMed1979

Left ventricular ejection power in coronary artery disease during atrial pacing.

Peak and mean left ventricular ejection power were measured during atrial pacing in 6 normal subjects (group I), 6 patients with coronary artery disease without myocardial infarction (group IIa), and 10 patients with coronary artery disease after myocardial infarction (group IIb). Pacing rates were 80 and 120/min. Power was determined by computer analysis of pressure, volume, and time. Data were normalised by end-diastolic volume and left ventricular muscle mass. Peak left ventricular ejection power normalised by end-diastolic volume values at a pacing rate of 120 min were significantly lower in group IIa and IIb than in normal subjects. Mean muscle mass in normal subjects was 179 g and in group IIa 216 g (P smaller than 0.05). Peak power normalised by muscle mass in normal subjects tended to increase at 120/min whereas in group IIa it declined by 26 per cent (P less than 0.001). These data indicate that the energy output of the left ventricle at rest may be the same in patients with significant coronary artery disease as in normal subjects. Increasing the heart rate from 80 to 120/min in a normal myocardium augments power but in coronary artery disease it remains static or falls.

Adult↗
PubMed1979

[Word field disturbances and sentence field disturbances as differential diagnosis criteria between endogenous and exogenous paranoid-hallucination syndrome].

Through the 'classical' psychopathological symptoms only, one sometimes cannot clearly differentiate between an endogenous and an exogenous psychosis. But through the identification of word field disturbances and sentence field disturbances, which are characteristic schizophrenic symptoms, one can put the diagnosis of schizophrenia in such cases. This diagnosis can be stated through the course of the illness and its therapy.

Adult↗
PubMed1979

[An interpretation deduced from word field disturbances and sentence disturbances in schizophrenia: a psychological study].

We investigated the occurrence of word field disturbances and sentence field disturbances in the text of schizophrenic patients. Through the connection of these disturbances with relevant biographical data of the patient and through a psychological interpretation we found that the occurrence of these disturbances is not accidental, but has a relevant psychological meaning for the patient.

Child↗
PubMed1979

[Cardiac effect of fenoterol alone or combined with Verapamil (author's transl)].

Two groups each consisting of twelve healthy students received Fenoterol (0,03 microgram/kg/min) alone or in combination with Verapamil (1,2 micrograms/kg/min) intravenously. In both groups, heart rate, arterial blood pressure amplitude and echocardiographically determined left ventricular contractility parameters increased significantly and equally. These results suggest that Verapamil does not counteract the positive chronotropic and inotropic effect of Fenoterol.

Adult↗
PubMed1979

[Pressure-dimension analysis of the poststimulation potentiation--influence of heart rate and ventricular function (author's transl)].

The mechanism of poststimulation potentiation (PSP) was studied in 17 patients with coronary artery disease by simultaneous pressure-dimension analysis. The left ventricular pressure (LVP) was measured by catheter-tip-micromanometer and LV diameter by M-mode echocardiography. The pressure signals were digitised and analysed on line by 400 Hz. The pressure-dimension tracings were additionally analysed half-automatically. Measurements were done during right atrial pacing at 80, 120, 140 beats/min and during the poststimulation period. 1. Right atrial pacing increased the rate of LV pressure development (dp/dt max), the rate of pressure fall (dp/dt min), the velocity of circumferential fiber shortening (VCF mn), and fiber dilatation (vcf mx) dependent on heart rate and cardiac function. 2. LV enddiastolic diameter (LVEDD) reached during the first poststimulation period the starting point independent on pacing rate and cardiac function. LV enddiastolic pressure (LVEDP) showed a slight overshoot. PSP resulted in an increase of LVP, dp/dt max, VCF mn, and the velocity of posterior wall motion, dp/dt min, VCF mx, and the velocity of posterior wall relaxation decreased, however, with the first post-stimulation beat. 3. The PSP was dependent on atrial pacing rate. The higher the pacing rate the higher the PSP. dp/dt max increased after cessation of 120/min for +29% and after 140/min for +38%. The PSP for the preload independent parameter of contractility, V-40, was, however, equal for both heart rates +25% and +28% respectively. 4. Another determinant of PSP was cardiac function. The PSP was relatively higher in patients with reduced ejection fraction than in patients with a normal ejection fraction: dp/dt max +55% and 25%, VCF mn +18% and +7% respectively. From the derived ventricular function curves, it could be shown, that atrial pacing reflected an increase in LV contractility (Bowditch effect), whereas PSP reflected an increase in LV performance by the Frank-Straub-Starling (Woodworth staircase) effect on a new left ventricular function curve, which was shifted to the left by atrial pacing.

Adult↗
PubMed1978

[Special diagnostic procedures in atrial tumours of the heart (author's transl)].

A vascular myxoma which prolapsed into the mitral valve was found in the left atrium of a 47-year old man. Two-dimensional ultrasonic tomography yielded relevant non-invasive diagnostic information on the pattern of movement of the pedunculated tumour. Highly accurate determination of the tumour volume was achieved via angiocardiography and videometry. Coronography of the tumour vessels allowed identification of an unusual point of insertion of the myxoma. The risk of obstruction of the mitral orifice was documented haemodynamically by a steep gradient above the mitral valve when holding breath during the expiratory phase.

Angiocardiography↗
PubMed1978

[Evaluation of regional myocardial dysfunction by echocardiographic pressure-dimension analysis (author's transl)].

Ecg, left ventricular pressure measured by micromanometer-tipped catheter, and dimension measured by echocardiography were simultaneously recorded in 24 patients with coronary artery disease and 9 normal subjects. In analogy to pressure-volume diagrams, pressure-dimension diagrams were constructed, the area in systole and diastole and the cycle efficiency calculated. In patients with coronary artery disease the normal rectangular shape of the pressure-dimension diagram shows two typical deviations: 1. a dimension decrease during isovolumetric contraction and dimension increase during isovolumic relaxation in 42% of the patients, in 31% in patients with stenosis of the right coronary artery, in 56% in patients with stenosis of the left anterior descending coronary artery, in 85% in patients with a reduced ejection fraction. 2. An exact reflected image was found only in patients with stenosis of the right coronary artery and reduced ventricular function in 23%. The abnormal dimension changes are the result of an asynchronized contraction and relaxation with inward movement of one part and outward movement of another part of the left ventricle. These changes are caused by ischemic or fibrous areas of the ventricle. Independent of left ventricular pressure and dimension changes we found that the cycle efficiency was useful to study regional myocardial work. It ranged from 81.7 +/- 2.5% in the normal subjects to 74.8 +/- 1.8% in patients with reduced ventricular function. From the diastolic part of the pressure-dimension diagram the regional compliance was calculated. Dependent on coronary artery disease the regional compliance was decreased even at rest.

Adult↗